226
Our analysis of the existing urban fabric followed the guidelines of the Technical
University of Vienna, which has proposed a number of indicators for weighing and
quantifying the various UHI production factors (Table 8.1).
We quantified these indexes and compared them to our temperature readings to
obtain cogent results that would approximate the real state of things. Thanks to this
approach we were able to evaluate the various urban microclimates of the selected
areas and single out incidence factors.
For example, the first area that we analyzed showed that heat island production
factors are mostly ascribable to the low ratio between permeable – impermeable
surfaces and the sky view factor, whereas the fourth area (which we later picked as
final pilot area) showed that heat production is mostly ascribable to the type of
materials used for buildings. Therefore, it seems obvious that mitigation strategies
(and the urban planning tools for implementing project interventions) must be different for the two areas in question.
In order to ensure and maintain the high effectiveness of the proposed interventions and solutions, it is essential that the different overheating causes and issues of
each area be carefully identified so as to come up with site-specific strategies.
The necessary information for evaluating (and then monitoring) the resilience of an
urban area to heat waves were the following:
Paved surface areas;
Permeable surface areas;
Built up surface;
Sky View Factor (SVF);
Urban compactness;
Solar incidence;
Reflectance/albedo of materials;
Thermal conductivity of materials;
Due to the great number of details provided by all this information, we had to
come up with an appropriate data collection method for our analysis. Two alternative methods were used; one was a traditional analysis on the field that classified
ground covering and building types as well as the height of buildings, the other used
remote sensing and three-dimensional data processing from LiDAR
2 and very high
resolution orthophotos.
The traditional method allowed us to map the urban tissue and determine the
types of materials of all the surfaces, as well as their thermal properties. This activity
required a lot of time, spent mainly on the field, but yielded a complete and current
set of facts for the area.
2 Il LiDAR (Laser Imaging Detection and Ranging) performs remote sensing to determine the
distance of an object or surface through the emission of high frequency laser pulses by a flying
sensor (plane or drone). The distance of an object is given by the length of time elapsed between
emission and reception. Very high frequency pulses bouncing from objects or the ground are converted into geo-referenced and dimensioned points, thus giving rise to a “point cloud” from which
the exact reconstruction of an area can be created in the form of three-dimensional digital models.
F. Musco et al.
Our analysis of the existing urban fabric followed the guidelines of the Technical
University of Vienna, which has proposed a number of indicators for weighing and
quantifying the various UHI production factors (Table 8.1).
We quantified these indexes and compared them to our temperature readings to
obtain cogent results that would approximate the real state of things. Thanks to this
approach we were able to evaluate the various urban microclimates of the selected
areas and single out incidence factors.
For example, the first area that we analyzed showed that heat island production
factors are mostly ascribable to the low ratio between permeable – impermeable
surfaces and the sky view factor, whereas the fourth area (which we later picked as
final pilot area) showed that heat production is mostly ascribable to the type of
materials used for buildings. Therefore, it seems obvious that mitigation strategies
(and the urban planning tools for implementing project interventions) must be different for the two areas in question.
In order to ensure and maintain the high effectiveness of the proposed interventions and solutions, it is essential that the different overheating causes and issues of
each area be carefully identified so as to come up with site-specific strategies.
The necessary information for evaluating (and then monitoring) the resilience of an
urban area to heat waves were the following:
Paved surface areas;
Permeable surface areas;
Built up surface;
Sky View Factor (SVF);
Urban compactness;
Solar incidence;
Reflectance/albedo of materials;
Thermal conductivity of materials;
Due to the great number of details provided by all this information, we had to
come up with an appropriate data collection method for our analysis. Two alternative methods were used; one was a traditional analysis on the field that classified
ground covering and building types as well as the height of buildings, the other used
remote sensing and three-dimensional data processing from LiDAR
2 and very high
resolution orthophotos.
The traditional method allowed us to map the urban tissue and determine the
types of materials of all the surfaces, as well as their thermal properties. This activity
required a lot of time, spent mainly on the field, but yielded a complete and current
set of facts for the area.
2 Il LiDAR (Laser Imaging Detection and Ranging) performs remote sensing to determine the
distance of an object or surface through the emission of high frequency laser pulses by a flying
sensor (plane or drone). The distance of an object is given by the length of time elapsed between
emission and reception. Very high frequency pulses bouncing from objects or the ground are converted into geo-referenced and dimensioned points, thus giving rise to a “point cloud” from which
the exact reconstruction of an area can be created in the form of three-dimensional digital models.
F. Musco et al.